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Bond Length differences between FULL (all electrons correlated) and FROZEN core

Such as MP2=Frozen and MP2=Full
17 10 27 16 27

For K2 atoms 1 and 2

For K2 (Potassium diatomic)
Bond length differences (full - frozen) in Å. Mouse over a difference for the bond length with full correlation.
Methods with standard basis sets
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP
Moller Plesset perturbation MP2=FULL 0.0145 0.0055 0.0480 -0.0001 0.0140 0.0001 0.0001 0.0825 0.0056 0.0006 0.0382
MP3=FULL         -0.0183   0.0022        
MP4=FULL   0.0052     0.0001       0.0041    
Coupled Cluster CCSD=FULL         0.0001           0.0255
CCSD(T)=FULL         0.0001           0.0212
STO-3G 3-21G 3-21G* 6-31G 6-31G* 6-31G** 6-31+G** 6-311G* 6-311G** 6-31G(2df,p) TZVP

k2.gif